TATA PUNCH-SERVICE MANUAL

1.2L REVOTRON ENGINE 43 4. ENGINE TESTS AND MAINTENANCE: A. PRELIMINARY INSPECTION : NOTE  It is always advisable to first use the diagnostic tool and rectify the electrical faults, before commencing with mechanical repairs/ troubleshooting. Refer ENGINE MANAGEMENT SYSTEM section in this group for procedure.  GENERAL : 1. Check for leakage of Oil, fuel, and Coolant. 2. Check for overheating of engine. 3. Check for unusual smoke. 4. If there is any fault in the Engine Management system (EMS) then the MIL indicator in the instrument cluster will come ON. In such a case connect the diagnostic tester. (For procedure refer EMS section). Before proceeding to carry out actual reconditioning of engine, it is desirable to have a preliminary inspection of engine to ascertain whether an engine reconditioning is necessary and if so, to what extent. Most common reasons for which engine is reconditioned are 1. Loss of power. 2. Excessive engine oil consumption. 3. Extremely low engine oil pressure. 4. Mechanical failures. To know exact reason and general condition of engine, proceed as follows i. LOSS OF POWER : Loss of engine power may be due to a. EMS is in limp-home mode due to some critical fault. b. Clogged air filter / exhaust passage / catalytic converter. c. Defective fuel system d. Clutch slippage e. Brake binding ii. EMS is in limp-home mode : If the EMS detects some major fault in the system it switches to limp-home mode, where it runs at a reduced torque. Connect the diagnostic tester and check if any faults are present in the Engine EMS, if found rectify them. (For details refer Engine Management Section) iii. Clogged Air filter / Loss of Charge Air Pressure/ Choked Exhaust Silencer / catalytic converter : Loss of power with unusual black smoke from engine exhaust indicates lack of air or low air charging pressure to engine cylinders. Clean air filter & inter cooler fins. Check all joints for air leakage. If power loss with black smoke is still felt, check exhaust silencer for choking. Clean and replace silencer if necessary. Check for kink formation in exhaust piping. iv. Defective Fuel System : Check the Fuel system for fuel flow. If the flow is restricted change the filter. v. Clutch Slippage : Clutch slipping can be confirmed by any of the following two methods:  Method 1 : 1. Drive the car in 1st or 2nd gear at a minimum speed corresponding to that gear. 2. With the accelerator pedal in a fully pressed position, gradually apply brake with left foot. 3. If the engine stalls, the clutch does not slip.  Method 2 : 1. Drive the gear with weight equal to GVW in 3rd gear on a level ground. 2. Allow the speed to drop upto 15kmph. 3. Now press the accelerator pedal fully. 4. With slipping clutch the car will not pick up speed, also a clutch burning smell could be noticed. 5. If this does not occur, the clutch does not slip. vi. Brake Binding : During driving apply brakes number of times and then shift gear to neutral position and check free rolling of vehicle. Check brake drums/brake discs for overheating and if necessary jack up the vehicle and check wheels for free rotation.